Lubricant composition



Patented July 2, 1940 UNITED STATES LUBRICANT COMPOSITION Elmer Wade Adams and George Mervin McNulty, Hammond, Ind., assisnors to Standard Oil Company, Chicago, 111., a corporation of Indiana No Drawing.

Application June 10, 1936,

Serial No. 84,525

4 Claims.

This invention relates to an improved lubricant for use on bearing surfaces which are subiected to high pressures, elevated temperatures,

nary mineral lubricating oils. Improved lubricants are also needed in the crank-case of automobiles on account of the use of alloy bearings such as the copper-lead and cadmium-silver bearings. The trend toward increasing loads on gear teeth in other fields has developed an urgent need for special lubricants. When hypoid gears,

worm gears, heavy duty bearings, alloy crank-' case bearings, planetary automatic shifts, and the 20 like are used under conditions of high pressure and high rubbing velocities, special types of lubricants such as those having extreme-pressure properties and/or non-corrosive properties must be provided in order to reduce the wear upon such moving parts. Extreme-pressure lubricants are likewise important in cutting and drawing operations where the oil must withstand high pressures encountered under those conditions of use.

The object of our invention is to provide a lubricant which will give satisfactory lubrication to bearing surfaces which are subjected to high pressures and/or high rubbing velocities as well 'as alloy bearings which tend to corrode on account of the action of the oil upon the bearing.

* A further object is to provide a lubricant which will maintain a lubricant film on bearing surfaces at all times. We have found that if small amounts of certain types of organic sulfur comm pounds are added to the lubricating oils and soft greases, the lubricant will enable the bearing surfaces to withstand the high pressures and high rubbing velocities without noticeable wear or corrosion. Similarly, these sulfur compounds may L5 be incorporated into drawing lubricants and cut ting oils.

We have found that the improved lubricants can be prepared by adding a small quantity of an alkyl disulfide, high molecular weight alkyl suli fides, aryl thiocyanates andaryl isothiocyanates,

xanthic disulfides, or xanthates to mineral lubrieating oils, preferably, those lubricating oils having a viscosity from about 90 to 200 seconds Saybolt at 210 F. These compounds may be used it in oils designated at S. A. E. 20, 30, 40, 50, and 60 oils. The oils designated by S. A. E. viscosity number have Saybolt viscosities ranging from 90 to 300 seconds at 130 F. These sulfur compounds are added in very small quantities. Amounts ranging from 0.1-1.0% to -7% may be used but generally amounts ranging from A; to 5% are satisfactory. The organic sulfur compounds may be dissolved in the oil by any conventional mixing means. If desired, calcium and aluminum soaps or other soaps of high molecular weight fatty acids may be added to the composition to increase the viscosity or consistency of the lubricant. These lubricants have substantially no corrosive action upon metal surfaces,

The sulfur-bearing compounds which may be added to mineral lubricating oils or greases to impart improved lubricating properties thereto are as follows:

I R-S-R1 Ra-SSRs Sulfldes Disulfldes Wherein R and R1 represent alkyl groups containing at least 5 carbon atoms each or aromatic groups such as phenyl radicals and tolyl radicals, however, when R represents a phenyl group, R1 may represent any alkyl group; and R2 and R3 represent alkyl groups or phenyl groups. The term alkyl is intended to include the saturated cyclic radicals also, such as the cyclohexyl group. Examples of the sulfides are amyl sulfide, hexyl sulfide, cyclohexyl sulfide, phenyl sulfide, ethyl phenyl sulfide, methyl phenyl sulfide, tolyl sulfide, and butyl phenyl sulfide. Examples of the disulfides are ethyl disulfide, n-propyl disulfide, n-butyl disulfide, secondary butyl disulfide, tertiary butyl disulfide, cyclohexyl disulfide, ethyl propyl disulfide, amyl disulfide, heptyl disulfide, tolyl disulfide, and phenyl disulfide.

II R4-SCEN R4-N=C- S Aryl thiocyanic esters Aryl isothiocyanic esters Wherein R4 represents aryl groups such as phenyl, tolyl and naphthyl groups. Examples of the hydrocarbon thiocyanic esters are phenyl thiocyanic ester, tolyl thiocyanic ester, and naphthyl thiocyanic ester. Examples of the aryl isothiocyanic esters or aryl isosulphocyanic esters are phenyl isosulphocyanic ester, tolyl isosulpho= cyanic esters, and naphthyl isosulphocyanic ester. Other hydrocarbon thiocyanic esters and isothiocyanic esters may be used, particularly those hydrocarbon derivatives containing six or more car= bon atoms in the hydrocarbon radical. The hydrocarbon radical may be of the straight chain type and may contain six, ten, twelve or more 55 wherein R5, Re and R7 represent alkylgroups.

Examples of the xanthic esters are ethyl xanthate ethyl ester, methyl xanthate ethyl ester, ethyl xanthate methyl ester, ethyl xanthate butyl ester and ethyl xanthate propyl ester. Examples of the xanthic disulfldes are methyl xanthic disulfide and ethyl xanthic disulfide.

The load-carrying capacity of these improved lubricants when used as extreme-pressure lubricants may be determined by the extreme-pressure testing machines such as the "Almen Extreme-Pressure Lubricant Testing Machine described by Wolf and Mou'gey in their paper on extreme-pressure lubricants given at the 13th Annual Meeting of the A. P. I. at Houston, Texas. November 17, 1932.

The following table illustrates the load-carrying capacity of the compositions when used as extreme-pressure lubricants as determined by an extreme-pressure lubricant testing. machine designed and operated on the'same principle as the Almen extreme-pressure lubricant testing machine. These lubricants may also be used to lubricate alloy bearings which are corroded by used mineral lubricating oils. v

Table I Sample.5% of the following compounds dissolved in zero bright stock (mineral oil having a viscosity of 150 Sa bolt at 210 F.)

peed of pin.--150 R. P. M.

may be added to the viscous mineral oil by any suitable means. Generally the sulfur compounds are added to the mineral oil and stirred until a homogeneous mixture is obtained. Coastal oils,

Mid-Continent oils and parafiin mineral oils may be used in the preparation of our improved lubricants.

Example Our improved lubricants may be prepared by mixing a small amount of one of the organic sulphur compounds with a" mineral oil having a viscosity suited for the particular use ofthe lubricant. A concentrated mineral oil solution of the particular sulphur compound may be added to a large portion of mineral oil or the desired amount of the organic sulphur compound may be mixed with the body of mineral oil to be treated.

The hydrocarbon derivatives of the compounds herein disclosed may be prepared by any of the conventional means. The disulfldes, for example, may be prepared from the mercaptans occurring in petroleum distillates boiling within the gasoline or kerosene range. A petroleum distillate, preferablytone containing a high percent of mercaptans, is agitated with caustic. The caustic solution is separated from the hydrocarbon material by decantation and then oxidized with any suitable chemical reagent, for example air, or oxygen. The alkyl disulfldes are then removed from the oxidized caustic solution by boiling and are collected by absorption in a mineral oil solution; if desired, they may be absorbed in the mineral oil used in the preparation of the extremepressure lubricant. The oxidationwith air or oxygen is preferably performed under pressure and at a temperature below the boiling point of the mercaptans in the petroleum distillate. Generally this temperature -is below to C. Other oxidizing agents such as hydrogen peroxide or potassium permanganate may be used instead of the oxygen. Also the high molecular weight alkyl disulfldes may be prepared by treating hydrocarbon distillates with sodium plumbite solution and sulfur, separating the plumbite solution from the 011 containing the dissolved disulfide and recovering the alkyl disulfldes by distilling the hydrocarbon oil from the dissolved disulfldes.

The present application is a continuattion-inpart of our copending application Serial 718,438, filed March 31, 1934. While we have described our invention with reference to particular examples, it should be understood that our invention is not limited thereby, except as set forth by the claims.

We claim:

1. An improved lubricant composition comprising a mineral lubricating oil and a small amount of an alkyl xanthic disulflde.

2. An improved lubricant composition compris ing a mineral lubricating oil and a small amount of a xanthic disulfide.

3. An improved lubricant composition comprising a mineral lubricating oil and a small amount of methyl xanthic disulilde.

4. An improved lubricant composition comprising a mineral lubricating oil and a small amount of ethyl xanthic disulfide,

' ELMZER. WADE ADAMS.

GEORGE MERVIN McNUL'IY. 

